// Copyright 2005 The Trustees of Indiana University.
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// Use, modification and distribution is subject to the Boost Software
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// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// Authors: Douglas Gregor
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// Andrew Lumsdaine
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#ifndef BOOST_GRAPH_PARALLEL_INPLACE_ALL_TO_ALL_HPP
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#define BOOST_GRAPH_PARALLEL_INPLACE_ALL_TO_ALL_HPP
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#ifndef BOOST_GRAPH_USE_MPI
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#error "Parallel BGL files should not be included unless <boost/graph/use_mpi.hpp> has been included"
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#endif
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//
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// Implements the inplace all-to-all communication algorithm.
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//
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#include <vector>
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#include <iterator>
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namespace boost { namespace parallel {
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template<typename ProcessGroup, typename T>
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// where {LinearProcessGroup<ProcessGroup>, MessagingProcessGroup<ProcessGroup>}
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void
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inplace_all_to_all(ProcessGroup pg,
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const std::vector<std::vector<T> >& outgoing,
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std::vector<std::vector<T> >& incoming)
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{
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typedef typename std::vector<T>::size_type size_type;
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typedef typename ProcessGroup::process_size_type process_size_type;
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typedef typename ProcessGroup::process_id_type process_id_type;
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process_size_type p = num_processes(pg);
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// Make sure there are no straggling messages
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synchronize(pg);
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// Send along the count (always) and the data (if count > 0)
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for (process_id_type dest = 0; dest < p; ++dest) {
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if (dest != process_id(pg)) {
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send(pg, dest, 0, outgoing[dest].size());
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if (!outgoing[dest].empty())
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send(pg, dest, 1, &outgoing[dest].front(), outgoing[dest].size());
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}
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}
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// Make sure all of the data gets transferred
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synchronize(pg);
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// Receive the sizes and data
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for (process_id_type source = 0; source < p; ++source) {
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if (source != process_id(pg)) {
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size_type size;
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receive(pg, source, 0, size);
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incoming[source].resize(size);
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if (size > 0)
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receive(pg, source, 1, &incoming[source].front(), size);
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} else if (&incoming != &outgoing) {
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incoming[source] = outgoing[source];
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}
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}
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}
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template<typename ProcessGroup, typename T>
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// where {LinearProcessGroup<ProcessGroup>, MessagingProcessGroup<ProcessGroup>}
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void
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inplace_all_to_all(ProcessGroup pg, std::vector<std::vector<T> >& data)
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{
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inplace_all_to_all(pg, data, data);
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}
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} } // end namespace boost::parallel
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#endif // BOOST_GRAPH_PARALLEL_INPLACE_ALL_TO_ALL_HPP
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